To achieve these aims, DO-HEALTH will enroll 2152 community-dwelling men and women who are 70 years and older, an age when chronic diseases increase substantially. The DO-HEALTH seniors will be recruited from 7 European cities (Zurich, Basel, Geneva, Toulouse, Berlin, Innsbruck and Coimbra) and will be randomized in a 2x2x2 factorial design trial to a simple home exercise program and/or vitamin D, and/or omega-3 fatty acids, over a 3 year period. This will allow to test the individual and the combined benefit of the interventions in the prevention of 5 primary endpoints: the risk of incident non-vertebral fractures; the risk of functional decline; the risk of blood pressure increase; the risk of cognitive decline; and the rate of any infection. Key secondary endpoints include risk of hip fracture, rate of falls, pain in symptomatic knee osteoarthritis, gastro-intestinal symptoms, mental and oral health, quality of life, and life-expectancy.